Selected Problems of Determining Critical Loads in Sructures with Stable Post-Critical Behaviour.

This paper presents selected cases of inapplicability of theory based methods of determining critical loads in thin – walled, composite tubes. 8th layered composite tubes with square cross-section were being subjected to static compression and in order to register experimental data two measuring equipment were employed: strain-gauges and Digital Image Correlation system ARAMIS R ⃝ . When measurement data were collected five different theory based methods were applied in order to determine critical loads. Cases where it was impossible to apply certain methods or some doubts about correctness of the results occurred were presented and analyzed. Moreover in cases where it was possible, the theory was equivalently transformed, in such a way to fit experimental data and calculate the critical loads

Experimental investigations of thin walled, squared cross – section composite tubes applied to static compression.

This paper deals with the experimental investigations of thin-walled, squared crosssection composite tubes subjected to a static compression. The main purpose of this paper is to present and discuss different methods of data analysis while investigating stability of thin-walled structures. Performed experiments were conducted by employing Zwick/Roel universal test stand; non-contact, geometrical - optical principled system Aramis produced by GOM company and strain-gauge technique. Different methods of determining buckling loads were employed, discussed and compared. Moreover all problems, occurring during experiments and data analysis were emphasized in order to show what kind of difficulties could appear during processing the results of measurements. As an example, comparing non-dimensional strain-gauges data with dimensional non-contact system Aramis results of measurements can quoted

Naprężenia badane pod supermikroskopem

Artykuł zamieszczony jest w : Życie Uczelni : biuletyn informacyjny Politechniki Łódzkiej, nr 155, Luty 2021Międzynarodowy zespół badawczy, w którego skład wchodzą prof. Tomasz Kubiak i jego doktorant mgr inż. Paweł Czapski z Katedry Wytrzymałości Materiałów i Konstrukcji Politechniki Łódzkiej we współpracy z University of Bath oraz Politechniką Lubelską otrzymał rekomendację do finansowania badań pt. Radiography and residual stress characterisation in thin-walled carbon fibre channel wykonanych przy użyciu synchrotronu Diamond Light Source w Wielkiej Brytani

Towards wireless sensor networks with enhanced vision capabilities

Wireless sensor networks are expected to become an important tool for various security, surveillance and/or monitoring applications. The paper discusses selected practical aspects of development of such networks. First, design and implementation of an exemplary wireless sensor network for intrusion detection and classification are briefly presented. The network consists of two levels of nodes. At the first level, relatively simple microcontroller-based nodes with basic sensing devices and wireless transmission capabilities are used. These nodes are used as preliminary detectors of prospective intrusions. The second-level sensor node is built around a high performance FPGA controlling an array of cameras. The second-level nodes can be dynamically reconfigured to perform various types of visual data processing and analysis algorithms used to confirm the presence of intruders in the scene and to classify approximately the intrusion, if any. The paper briefly presents algorithms and overviews hardware of the network. In the last part of the paper, prospective directions for wireless sensor networks are analyzed and certain recommendations are included

System-level methods for power and energy efficiency of FPGA-based embedded systems

Field programmable gate array (FPGA) processing units present considerably higher programming flexibility than other fixed architectures (e.g. microcontrollers (MCU’s), digital signal processors (DSP’s)). Although performances of FPGA are often compared to application-specific integrated circuits (ASIC’s), the price for such a flexibility of programmable devices is a significantly higher power consumption, compared to other fixed-architecture processors. Power consumption of FPGA implementations can be reduced at the low-level of design. However, for designs of moderate and high complexity such low-level approaches are tedious to implement and time-consuming. High (system) levels of design (e.g. algorithmic languages such as Handel-C) allow building systems of significantly higher complexity. Unfortunately, high-level design techniques have a limited (or no at all) ability to control power/energy properties of a design. The objective of our work is, therefore, to investigate the system-level approaches to power (and energy) efficiency of FPGA-based devices. FPGA’s dissipate static and dynamic power. However, only the dynamic power consumption is design-dependent, while static power consumption is mainly technology-dependent. Thus, we generally ignore the issues of static power reduction in the presented results. First, we show that power and energy properties of FPGA-based designs can be estimated with a reasonable precision at the high level of designing process. Moreover, we show that the system-level partitioning of designs into several clock domains (typically used to improve performance only) does not noticeably affect power consumption and hardware resources compared to the equivalent low-level partitioning. These two observations are the foundations of further experiments on system-level approaches to power and energy efficiency. We separately analyze the system-level parallel and sequential algorithm partitioning (in both cases employing the concept of multi-clock domains). It is shown that parallel algorithm partitioning can be optimized (by exploiting system-level estimates of domain sizes and timing) to provide substantial power consumption savings. Sequential partitioning was found a less efficient tool for reducing power and energy consumption of designs. However, we found that in sequentially partitioned designs power consumption losses can be minimized by selecting proper clock frequencies of a particular domain, if for certain reasons the domains must be run at diversified frequencies (which generally dramatically increases the overall energy usage). Finally, we analyze the total consumption of data-processing and data-transmission energies in FPGA-based designs (which is a typical problem for wireless sensor network (WSN) applications). In general, hardware requirements (i.e. power and energy) of data processing algorithms grow proportionally to the amount of data processed concurrently, while the energy required for transmission is proportional to the volume of transmitted data. We show that by combining system-level algorithms properties and characteristics of transmission modules, substantial savings of the overall energy are achievable. We believe that the proposed solutions will lead to more advanced system-level approaches to power and energy efficiency, i.e. development of tools incorporating low-level power and energy characteristics into high-level design methodologies. Such tools would have the ability to control low-level characteristics (e.g. power and energy consumption) of FPGA-based designs from the highest levels of abstraction.DOCTOR OF PHILOSOPHY (SCE

Maternal Immune Activation Induces Neuroinflammation and Cortical Synaptic Deficits in the Adolescent Rat Offspring

Maternal immune activation (MIA), induced by infection during pregnancy, is an important risk factor for neuro-developmental disorders, such as autism. Abnormal maternal cytokine signaling may affect fetal brain development and contribute to neurobiological and behavioral changes in the offspring. Here, we examined the effect of lipopolysaccharide-induced MIA on neuro-inflammatory changes, as well as synaptic morphology and key synaptic protein level in cerebral cortex of adolescent male rat offspring. Adolescent MIA offspring showed elevated blood cytokine levels, microglial activation, increased pro-inflammatory cytokines expression and increased oxidative stress in the cerebral cortex. Moreover, pathological changes in synaptic ultrastructure of MIA offspring was detected, along with presynaptic protein deficits and down-regulation of postsynaptic scaffolding proteins. Consequently, ability to unveil MIA-induced long-term alterations in synapses structure and protein level may have consequences on postnatal behavioral changes, associated with, and predisposed to, the development of neuropsychiatric disorders